School of Engineering and Information Technology, University of New South Wales, Canberra, ACT 2600, Australia.
Phys Rev E. 2019 Feb;99(2-1):023101. doi: 10.1103/PhysRevE.99.023101.
The dynamic characteristics of a two-dimensional deformable capsule in a simple shear flow are studied with an immersed boundary-lattice Boltzmann method. Simulations are conducted by varying the Reynolds number (Re) from 0.0125 to 2000 and the dimensionless shear rate (G) from 0.001 to 0.5. The G-Re plane can be divided into four regions according to the deformation dependence on the parameters considered: viscous dominant, inertia dominant, transitional, and anomalous regions. There are four typical dynamic behaviors over the G-Re plane: steady deformation, prerupture state, quasisteady deformation, and continuous elongation. Analysis indicates that the pressure distribution and its variations due to the interplay of the fluid inertia force, the viscous shear stress, and the membrane elastic force determines the complex behaviors of the capsule. The effects of the bending rigidity and the internal-to-external viscosity ratio on the dynamics of the capsule are further studied. It is found that the capsule experiences smaller deformation when the higher bending rigidity is included, and the low bending rigidity does not have a remarkable influence on the capsule deformation. The capsule normally experiences smaller deformation due to the increase of the internal-to-external viscosity ratio.
采用浸入边界-格子玻尔兹曼方法研究了二维可变形胶囊在简单剪切流中的动力学特性。通过改变雷诺数（Re）从 0.0125 到 2000 和无量纲剪切率（G）从 0.001 到 0.5 来进行模拟。根据所考虑参数的变形依赖性，G-Re 平面可以分为四个区域：粘性主导、惯性主导、过渡和异常区域。在 G-Re 平面上有四种典型的动力学行为：稳态变形、破裂前状态、准稳态变形和连续伸长。分析表明，压力分布及其由于流体惯性力、粘性剪切应力和膜弹性力的相互作用而产生的变化决定了胶囊的复杂行为。进一步研究了弯曲刚度和内外粘度比对胶囊动力学的影响。结果发现，当包含较高的弯曲刚度时，胶囊经历较小的变形，而低弯曲刚度对胶囊变形没有显著影响。由于内外粘度比的增加，胶囊通常经历较小的变形。
